Electrode mounting in electron discharge tube



1947- c. E. MURDOCKYET AL 7 ELECTRODE MOUNTING IN ELECTRON DISCHARGE TUBE Filed Aug. 14, 1945 4 Sheets-Sheet 1 INVENTORS I16 U/ayfon E. Murdock I Aober Levy/7 No fan 1 11 MEL,

THEIR ATTORNEY Sheets-Sheet 2 INVENTORS C/ayfon E. Murdock fobefif Leg/1 L/orfon THEIR ATTORNEY Dec. 2, 1947. c. E. MURDOCK ETAL ELECTRODE MOUNTING IN ELECTRON DISCHARGE'TUBE Filed Aug. 14, 1943 1947- c. E. MURDOCK ETAL 2,431,767

ELECTRODE MOUNTING IN ELECTRON DISCHARGE TUBE Filed Aug. 14, 1943 4 Sheets-Sheet 3 INVENTORS flag fan E. Murdock 5 R0 Zrf Leg/1 orfon mam ATTORNEY Dec. 2, 1947. c. E. MURDOCK ETAL 2,431,767.

ELECTRODE MOUNTING IN ELECTRON DISCHARGE TUBE Filed Aug. 14, 1943 4 Sheets-Sheet 4 27 .n D [W52 46 L F F 2 25 ILL' IO J 45 2 n p 49 L uxr m 6 2/ r a I j Z4 l 6? 4 4a 0 o 49 g ii I f/ mvr-zm-ons glzyfgnL E Ziurdgck 0 e e/ or on BY Fig.8 xXX/i,

THEIR ATTORNEY Patented Dec. 2,

ELECTRODE MOUNTING IN ELEc'moN DISCHARGE TUBE Clayton E. Murdock, Mlllbrae,

Norton, Burlingame, Callf.,

McCullough, Inc., tlon of California and Robert Leigh asslgnors to Eltel- San Bruno, 011111., a corpora- Application August 14, 1943, Serial No. 49mm; 11 Claims. (01. 25047.5)

Our invention relates to an electron tube for transmission purposes, and more particularly to a tube adapted for pulse work for radar use.

It is among the objects of our invention to provide a tube capable of delivering high power outputs, say of the order of one megawatt peak power from a four tube oscillator.

Another object is to provide improvements in the structure of and mounting for the various parts of the tube.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention as we may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure 1 is a side elevational view of the preferred tube embodying the improvements of our invention.

Figure 2 is a detail elevational view of the his.- ment prior to mounting on the stem; and

Figure 3 is a horizontal sectional view of the same taken in a plane indicated by line 3-3 of Figure 2.

Figure 4 is a vertical sectional view of the completed tube; and

Figure 5 is a plan view of the same.

Figure 6 is a detail elevational view of the grid prior to mounting in the envelope.

Figures 7, 8 and 9 are elevational, vertical sectional and plan views, respectively, of a modified tube having grid leads at one end only.

Figure 10 is a diagrammatic plan view showing the preferred arrangement of four tubes in an oscillator.

In terms of broad inclusion, our improved tube comprises an envelope enclosing a plate and grid and cathode. These electrodes are coaxially arranged in the tube, the plate andgrid being supported on laterally extending conductors sealed to the side walls of the envelope to provide short leads. In the preferred construction the grid is supported at both ends. The cathode is of the filamentary type comprising vertical bars of thoriated tungsten arranged in groups or sections arcuately disposed about the axis: each group being connected at one end to a separate filament lead and all being connected at the other end to a commonterminal cap. The cathode is supported on a stem at one end of the envelope and embodies a filament tensioning device. Improvements are also provided in the base for the tube and in the method of assembling the electrodes in the envelope.

In greater detail, and referringparticularly to Figures 1 to 6 of the drawings, our preferred tube structure comprises an envelope of glass or the like having a cylindrical body section 2 which prior to the final sealing operations is open at both ends. Reduced neck section 3 is fused to the body section along seal I, and reentrant stem 8 is fused to the neck at seal 1. The upper end of the envelope is closed by a top section 8 fused to the body at seal 9. This top section carries the exhaust tubulation which is finally sealed off at tip ii. The tube base comprises a metallic shell l2 secured to neck 3 by cement I 3. A disk ll of insulating material serves to support a hollow metallic center prong l6. During operation of the tube the stem is cooled by air admitted through prong l6 and exhausted through vent openings l'l.

Plate or anode I 8 is preferably a finned structure of tantalum made of arcuate sections forming a cylindrical body and having flanges welded together to form heat radiating fins l9. The fins preferably have curved outer edges. providing increased width at the intermediate portions. Flanged end rings 20 give added rigidity to the plate. This hollow plate is positioned about midway between the ends of envelope body section 2 and is disposed coaxially therewith. If desired a finless plate may be used. but, in the absence of a special surfacing to increase heat radiation, the fins are preferred.

Supporting and conductor means'for the plate is provided by a single lead 2|, preferably of tungsten, sealed to a horn 22 projecting from a side of envelope body section 2, Plate lead 2| is disposed laterally of the plate axis, the lead axis preferably intersecting the plate centrally thereof. Supporting bracket 23 of tantalum is conical in shape, slotted to straddle a fin, with its diverging end welded to the plateand its converging end embracing lead 2i and welded thereto with an interposed nickel sleeve 25. This arrangement provides a rigid plate support with a short, direct current path to this electrode.

Grid 2| is preferably the cage type comprising vertical wire bars terminating at end rings 28 andhaving a reinforcing spiral welded to the bars. Any suitable material having low primary emission properties may be used for the grid. Conical or hemispherical end pieces 21, say of tantalum, are welded to grid rings 28, these pieces flaring outwardly from the ends of the grid to aflord rigid mounting members and to form s eamer 3 shields protecting the envelope against electron bombardment.

Supporting and conductor means for the grid is provided by four leads 23, preferably of tungsten, arranged in pairs, two above and two below the electrode structure. These grid leads preferably lie in a common plane passing through the tube axis perpendicular to the plate lead, the grid leads being aligned in pairs disposed transversely of the grid and sealed to horns 29 projecting from opposite sides of envelope body section 2.

Grid 24 is supported by suitable brackets 3| bridged across the inner ends of leads 23. For purposes of resilience and to allow free axial expansion in the grid structure brackets 3| are preferably fiat tantalum straps diverging from the leads and spot welded to mid points on the rims of cones 21. These strap-like brackets are formed with a slight angle therein, as seen in Figure 4, to give added flexibility to the mounting. Tabs 32 on the ends of the brackets are welded to leads 23 with interposed nickel sleeves 33. This structure supporting the grid at both ends is preferred because the grid is positively held in axial alignment with the other electrodes, while at the same time elongation is permitted to take care of expansion. The laterally disposed leads also provide short current paths to the grid.

It will be noted that both the plate and grid are mounted on body section 2 of the envelope, which section is an open ended blank at the time these parts are assembled. This enables an operator to work in from both ends, using jigs to best advantage, and in general facilitating alignment and positioning of the parts. The preferred procedure is to first seal on horns 22 and 29 and then seal in the plate and grid leads. Next the plate and grid assemblies, with brackets 23 and 3i attached thereto, are inserted through an open end of the blank and the brackets welded to the respective leads. Neck section 3 is then sealed to the body section, which makes the envelope ready for receiving the filament stem.

The filament or cathode comprises a multiplicity of say 40 parallel wires 34 of thoriated tungsten divided into four groups disposed in cylindrical formation about the cathode axis, each group of wires being connected at the lower end to one of the four cathode leads 38 and all being connected at the upper end to a common terminal 31. Brackets 33 on the reduced upper ends of leads 36 are welded to quadrant rings 33 having arcuate rims to which the groups of filament wires are welded. This provides fixed supports for the lower ends of the filament wires. Cathode leads 36 of tungsten are sealed in a fourway press 4| on stem 6. Upper terminal 31 is a cap having a circular rim to which the upper ends of the filament wires are welded. This terminal provides a movable support and is held centered by a rod or standard 40 sealed to the stem and projecting through the cap. Tension is simultaneously applied to all the filament wires by a sleeve 42 slidable along the center rod and urged upwardly against cap 31 by a spring 43 interposed between the sleeve and stem. Disk 44 on the sleeve provides a shield for protecting the stem against electron bombardment.

Extensions 4!, preferably of copper tubing, are provided between the lower ends of the oathode leads and the base, a pair of diametrically opposed leads being soldered to prong It at joints 46 and the other pair being soldered to shell I2 at joints 4!. Integral strips bent inwardly from the side walls of the prong and shell at the joints give additional support and provide openings through which the solder is flowed. Filament heating current is applied to shell l2 and prong I! through a suitable socket. By this parallel connection the filament groups are simultaneously heated, it' being understood that two of the filament groups are connected in series with a pair of the leads and that the other two groups are connected in series with the other two leads. This structure has the advantage of compacting a multiplicity of filament wires in a relatively small circle, whereby a large amount of electron emitting surface is made available.

After the filament stem has been sealed in place the envelope is closed by sealing on top section 0. The tube is now ready for pumping, after which the exhaust tubulation is sealed off at point ll. Base l2-l6 is then cemented in place and the lead extensions soldered.

Our improved tubes are capable of delivering high power outputs particularly adapted for pulse work for radar use. For example, we have obtained outputs in excess of one megawatt peak power from a four tube oscillator. These tubes each had a set of electrodes approximately 1% inches long, including a plate, grid and filament having diameters of about 1.0 .6 and .5 inch, respectively, the filament comprising 40 wires of .0135 inch diameter thoriated tungsten.

Figures 7, 8 and 9 show a modified tube having a single pair of grid leads. In this case the leads 48 extend through the envelope along axes disposed apart and from the plate lead. The inner ends of the grid leads are bent out into parallelism and carry brackets 49 welded to lower grid cone 21. Another variation from the preferred construction is that body section 2 of the envelope has a closed top instead of being initially open at both ends. The exhaust tabulation ii is sealed to stem 6 as seen in Figure 8. Otherwise the arrangement and structure of the parts is similar to that first described.

In either case the improved arrangement of the grid and plate leads allows the tubes to be positioned to best advantage in an oscillator as indicated diagrammatically in Figure 10, with the plate leads tied closely together at a common center terminal 52 and the grid leads juxtaposed for connection with the grid tank circuits 53. This places the tubes closely together with short leads from the circuit components to the electrodes.

We claim:

1. An electron tube comprising an envelope, a plate and grid and cathode disposed about a longitudinal axis in the envelope, a pair of lateral grid leads extending through the side wall of the envelope, means supporting the grid on said leads, a single lateral plate lead extending through said side wall, means supporting the plate on the last mentioned lead, and conductor means for the cathode extending through an end of the envelope.

2. An electron tube comprising an envelope, a plate and grid and cathode disposed about a longitudinal axis in the envelope, a pair of lateral grid leads extending through the side wall of the envelope, means supporting the grid on said leads, a lateral plate lead extending through said side wall and lying in a plane bisecting an angle between said grid leads, means supporting the plate on said plate lead, and conductor means for the cathode extending through an end of the envelope.

3. An electron tube comprising an envelope, a plate and grid and cathode disposed about a longitudinal axis in the envelope, upper and lower grid leads extending through the envelope, supports on the leads connected to the ends of said grid, at least one of said supports being yieldable to permit axial expansion of the grid, and conductor means for the plate and cathode extending through the envelope.

4. An electron tube comprising an envelope, a plate and grid and cathode disposed about a longitudinal axis in the envelope, upper and lower pairs of lateral grid leads extending through the side wall of the envelope, means adjacent the top of the grid supporting it on the upper pair of leads, means adjacent the bottom of the grid supporting it on the lower pair of leads, a single lateral plate lead extending through said side wall, means supporting the plate on the last mentioned lead, and conductor means for the cathode extending through an end of the envelope.

5. An electron tube comprising an envelope, a plate and grid and cathode disposed about a longitudinal axis in the envelope, upper and lower pairs of lateral grid leads extending through the .side wall of the envelope, means adjacent the top of the grid supporting it on the upper pair of leads, means adjacent the bottom of the grid supporting it on the lower pair of leads, at least one of said supporting means being yieldable to permit axial expansion of the grid, and conductor means for the plate and cathode extending through the envelope.

6. An electron tube comprising an envelope, a plate and grid and cathode disposed about a longitudinal axis in the envelope, upper and lower pairs of lateral grid leads extending through the side wall of the envelope, means adjacent the top of the grid supporting it on the upper pair of leads, means adjacent the bottom of the grid supporting it on the lower pair of leads, said grid leads lying in a common plane, a lateral plate lead extending through said side wall and positioned perpendicularly to said plane, 'means supporting the plate on said plate lead, and conductor means for the cathode extending through an end of the envelope.

7. A cathode structure comprising a movable cup-shaped support having a circular rim, a fixed support having an arcuate rim aligned with that of the movable support, a group of parallel separate filament wires terminating at one end at the movable support and at the other end at said fixed support, means securing said ends of the wires to the rims of said supports, and means applying a force to the movable support to simultaneously tension the wires in said group.

8. A cathode structure comprising a plurality of groups of parallel separate filament wires disposed in cylindrical formation about the cathode axis, a movable cup-shaped support having a circular rim adjacent the upper ends of the wires, a plurality of fixed supports having arcuate rims arranged in a circle adjacent the lower ends of the wires, means securing the lower ends of said groups of wires to the rims of the fixed supports, means securing the upper ends of the wires to the rim of the movable support, and means applying a force to th movable suport to simultaneously tension the wires in said groups.

9. An electron tube comprising an envelope, a cathode in the envelope, a metallic base shell secured at one end to the envelope, an insulating disk at the other end of said shell, a metallic prong projecting from the center of said disk, a passage through said prong and disk for admitting a cooling fluid Within the base shell, an opening in the shell for discharging the fluid, and

. connectors leading from the cathode and secured to said shell and prong.

10. An electron tube comprising an envelope, a cathode in the envelope, a metallic base shell secured at one end to the envelope, a metallic prong projecting from and secured to the other end of said shell, a passage for cooling fluid in said prong, and connectors leading from the cathode and secured to said shell and prong.

11. An electron tube comprising an envelope, an open-ended tubular plate supported in the envelope, a grid extending through the plate, upper and lower pairs of grid leads projecting into th envelope, grid supporting means connected to the top of the grid and secured to the upper pair of leads, and grid supporting means connected to the bottom of the grid and secured to the lower pair of leads, at least one of said supporting means being yieldable to permit axial expansion of the grid.

CLAYTON E. MURDOCK. ROBERT LEIGH NORTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 383,616 Byllesby et al May 29, 1888 665,459 Painter Jan. 8, 1901 1,067,024 Hall et al July 8, 1913 1,555,677 Leblanc Sept. 29, 1925 1,720,442 Robinson July 9, 1929 1,750,238 McIlvaine Mar. 11, 1930 1,816,682 Langmuir July 28, 1931 1,927,084 Depew Sept. 19, 1933 1,965,338 Gibson et a1 July 3, 1934 1,991,174 Rose, Jr. Feb. 12, 1935 1,994,219 Hollmann Mar. 12, 1935 2,000,990 Samuel May 14, 1935 2,030,362 Eitel et al. Feb. 11, 1936 2,113,671 Zottu et al Apr. 12, 1938 2,165,135 Garner July 4, 1939 2,236,859 Vandegrift Apr. 1, 1941 2,245,998 Pietsch June 17, 1941 2,314,037 Eitel et a1 Mar. 16, 1943 2,333,622 McNat Nov. 2, 1943 2,335,587 Eitel et al Nov. 30, 1943 FOREIGN PATENTS Number Country Date 170,954 Great Britain Nov. 3, 1921 521,199 Great Britain May 15, 1940 528,688 Germany July 2, 1931 649,292

Germany Aug. 20, 1937 

